Core barrel



Oct. 28, 1941. A. MUHLBACH com: BARREL Filed nec. 24, 1958 ATTORNEY l N V EN TO R Alfred Mah/bach l Il fill!!! III Patented Oct. 28, 1941 UNITED STATES PATENT OFFICE com: BARREL Aurea Mumbacanos Angeles, caux. Application December 24,'19'38, Serial No. 247,625

.'(ci. s55- 12) 4 Claims.

This invention relates to` core barrels, such `as are used in connection with core drills in oil well drilling,-for securing' sections of the forma:

the core, while the outer shell rotates with the A drill.

It is another object of this invention to provide an improved bearing structurefor supportt l ing the inner shell in such a core barrel.

It is a principal object of this invention. to provide an improved and simplied core barrel oi this type.

It is anotherobject of this invention to provide a core barrel construction wherein the inner or stationary shell is resiliently maintained on its supporting surface on the bit by a force that is substantially constant at all times.

It is still another object of this invention to f provide an arrangement wherein this pressure is so maintained automatically.

It' is a still further object of this invention to provide a simplified and improved form of core catcher.

This invention possesses many other advantages, a'nd has other objects which may be made' more easily apparent from a consideration ofI one embodiment of the invention. For this purpose there is shown a form in the `drawing accompanying and forming part of the `present specication. This form will-now be described in detail,` illustrating the general principles of lthe l invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of .this invention is best defined vby the appended claims.

In the drawing: I

Figure 1 is a vertical section, showing the core barrelassembled with a conventional core drill in operating position in a well bore;

Fig. 2 is a detail section on an enlarged scale of the upperr end of the core barrel; and

Fig. 3 is a similar section of the lower end, showing the core catcher.

Referring to the drawing, a core drill generally indicated by 5 is shown which may be lone of various types in common use. It includes a shell 6 secured at its upper end, by means of suitable coupling members I and 8, to the drill string, and carries at its lower end the core bit III.

Within the shell 6 is disposed the core barrel I2,

which receives the core I3 as it is cut by bit I0, the core I3 remaining stationary while the 'drill rotates and advances downwardly.

To retain the core in the barrel when the drill is withdrawn from the bore, a core catcher Il is provided at the lower end of the barrel. To prevent damage or destruction of the core by contact with a. rotating member, the barrel` I2 is provided with an inner shell I6 for receiving the core and which is so supported relative to the drill y,that it may remain stationary while the latter is rotated. This protects the core.

The lower end of shell I6 rests on the core catcher I4 which in turn is supported in an annular recess I 'I having a shoulder I8 in bit I0. The core catcher is free to turn on its support, and is restrained against upward movement by the shell I6.

The upper end of shell I6 is suitably supported for permitting relative rotation between shells I8 and 20, by a combined radial and thrust bearing I9 carried in the outer shell 20 of the core barrel. Bearing I9 is preferably of some antifriction type so that the inner and outer shells are freely relatively rotatable under conditions of use. For example, a roller bearing may be used. It is not necessary tor provide any bearing i at the lower-end of barrel IG, since when a core shoulder I8.

is in the welll.

vthe shoulder Aand contacting parts.

Thus, the inner or stationary shell I6 is conilned between shoulder I8 and bearing I9, As it is desirable thatl the shell be freely rotatable. with respect to its supporting bearings, and at the same Ytime that the clearance at shoulder I8 'should be suiiiciently close to substantially prevent passage of the circulation luidffrom the inside ofthe barrel I2 into the core space at this point, means must be provided for holding the core shell I6 and core catcher Il against Manual adjustment of the axial position of the upper bearing I9, for providing a sufllcient seat between the relatively moving parts, is difficult to make after the tool is assembled, and of course impossible while the tool Further, since the length of the core barrel usually exceeds twenty feet. variations in temperature as well as other operating conditions would necessitate frequent adjustment. The requirement for adjustment is obviated in theI present instance by a compression spring 2| confined within shell 20 and acting against bearing I9 to urge the inner shell I8 and the core catcher Il downwardly tqseat I9. The structure whereby the spring 2| is rendered effective will now be described.

'The outer shell 2l) is secured at its lower end to bit I 0, as by a threaded portion 22, and

a head 32, threaded into shell I6.v

and urges member downwardly. To prevent,

the spring 2| and cup 25 dropping out of cap 23 when this is removed from the barrel, the cup 25 has its midportion of reduced diameter, forming shoulders 28, 30. A stop pin 3| mounted in the ,wall of the cap 2,3 extends into this space, and by engaging sl'oulder 29 holds the cup from coming-out of the cap but at the same time allows it to move in response to the movement of the inside shell. Spring 2| is strong enough to ensure that the frictional forces acting to move the inner shell I 6 upwardly are overcome and to ensure a satisfactorily tight iit between the bottom of the shell I6 and the rotating bit structure.

The inner shell I6 is closed at its upper end by Head 32 is provided with ports 33 in its Walls, some of which may be elongated to give greater area, to 'permit the discharge of circulation uid or other well liquids from the inside of shell I6 as the core I3 rises therein. A hub 34 on top of the head 32 carries the inner race 5| of bearing I9, as by being pressed on. A plurality of. conical rollers 35 secured in a cage 36 vare interposed between the races in a well understood manner.

The-lower end oi the inner shell I6 rests on an annular shoulder 3l formed in ring 3,8 of core catcher I4. The lower part of the inside surface of this' ring is bevelled' at a fairly steep angle as indicated by 39. On this surface are secured as by rivets 40,' a number of spring fingers 4I. By this arrangement, the fingers 4I are given an u'pward and inward inclination without the necessity of bending them. The upperparts 42 of the fingers 4| are tapered to a point and are curved inwardlyvso as closely to approach each other. By having the fingers 4I straight at the point where the flexing occurs, a stronger and m'ore resilient finger results; at the same time, the 'manufacture is simplified.

A protector ring 43 is used to cover the inside of the rivets and the lower parts` of the springs,

' discharge openings adjacent the loweredges of blades 45 serve to direct the circulation fluid.

' This fluid is forced downwardly through the drill string and reaches thel ports through the an nular space between shell 6 and the core barrel I2.

The conical cap 24 serves to direct this fluid, which may. be heavy mud, into this annular space 'with a minimum of resistance. As core I3 rises within inner shell I6, the circulation fluid of mud therein is displaced outwardly through ports 33 into the annular space between shells .I6 and 26, and thence downwardly and out into the well through ports 43.

As the core I3 passes into the inner shell I6 past the core catcher I4, the fingers 4I are bent outwardly as indicated in Fig. 1, the extent of this bending depending on the hardness of the core. Due to the closeness with which the upper vends 42 of the fingers 4| approach each other,

the catcher will be effective to hold cores of very soft material.

The mud fluid entering the annular space between the inner and outer barrels I6 and 20, reaches the core catcher assembly and serves in some measure to lubricate the bearing between the inner core barrel I6 and the core catcher.

What is claimed is:

1. In a core drill, an outer rotary tubular member having a bit secured at its lower end, a core barrel including a rotary outer shell secured to the bit and an inner shell rotatably supported at its lower end on the bit and guided at its upper end by bearing means, a guide member slidable axially within the outer shell and supporting the bearing means, a closurevfor the upper end of the outer shell, and resilient means interposed between the guide member and the closure for urging .the bearing and inner shell downwardly.

2. In a core drill, an outer rotary tubular member having a bit secured at its lower end, a core barrel within said shell, there being an annular space between the shell and the barrel to permit circulation fluid to pass downwardly to ports in the bit, said core barrel including a rotary outer shell secured to the bit and an inner shell rotatably supported at its lower end on the bit and guided at its upper end by bearing means, a guide member slidable axially within the outer shell and supporting the bearing means, a closure for the upper en`d of the outer shell, said closure being of tapered configuration so as to guide the circulation fiuid into the annular space with low resistance, and resilient means interposed between the guide member and the closure for urging the bearing and inner shell down' wardly. f

3. In a core drill, an outer rotary tubular member having a bit secured at its lower end, a core barrel including a rotary outer shell secured to the bit and an inner shell rotatably supported at its lower end on the bit, said outer shell having an inner cylindrical guiding surface adjacent its upper end, and bearing means slidably supportedface adjacent its upper end, a combined radial and thrust bearing adjacent the upper end of the inner shell, said bearing being slidably supported for axial movement in said guiding surface, and means resiliently urging the bearing and the inner shell downwardly in the outer shell.

ALFRED MUHLBACH. 

